Include documents inside a project reside in an Include Folder. This is a dedicated folder made into an Include folder by entering its path in Include Folders and Libraries in the project's configuration. A project can have as many Include Folders as needed.
In this way all Model Documents in a project can use these building blocks, but no other project can use them. To make it possible to use an Include Document, Text Block, Form, Field Set, View, DID, Data Backbone, or Style Document in all projects of the ITP/MDK Repository, Library projects have been invented.
Although a Library project is a normal project in every respect (you can store Model documents in it, you can create Models and so on) it is special in that its Paths can be searched and used by all other projects in the ITP/MDK Repository and that its Text Blocks, Forms, Field Sets, Views, DIDs, Data Backbones, and Style Documents can be used by other projects. A project is changed to a Library by selecting Library as its project type on its Project tab.
To use a building block from a Library Project that Library must be added to the Include Folders and Libraries setting in a projects configuration. Apart from the document in the include folders of the Library, also the documents in the root of the Library project are considered to be include documents by the projects that use the Library.